Method, compositions and kits for increasing the oral bioavailability of pharmaceutical agents

ABSTRACT

A combination of 9, 10-dihydro-5-methoxy-9-oxo-N-[4-[2-(1,2,3,4-tetrahydro-6,7, -dimethoxy-2-isoquinolinyl)ethyl]pheny]-4-acridinecarboxamide or a salt thereof and paclitaxel and its analogs or derivatives.

[0001] The invention relates to methods, compositions and kits forimproving the oral bioavailability of pharmaceutical agents that arepoorly absorbed from the gastrointestinal tract, and to methods oftreatment of patients through the oral administration of such agents.One aspect of the invention relates to the use of9,10-dihydro-5-methoxy-9-oxo-N-[4-[2-(1,2,3,4-tetrahydro-6,7-dimethoxy-2-isoquinolinyl)ethyl]phenyl]-4-acridinecarboxamideand physiologically acceptable salts and solvates thereof to enhance theoral bioavailability of paclitaxel and related taxanes.

[0002] Many valuable pharmacologically active compounds cannot beeffectively administered by the oral route because of poor systemicabsorption from the gastrointestinal tract. All these pharmaceuticalagents are, therefore, generally administered via intravenous orintramuscular routes, requiring intervention by a physician or otherhealth care professional, entailing considerable discomfort andpotential local trauma to the patient and even requiring administrationin a hospital setting with surgical access in the case of certain IVinfusions.

[0003] It has been speculated that, in some cases, the poorbioavailability of a drug after oral administration is a result of theactivity of a multidrug transporter, a membrane-bound P-glycoprotein,which functions as an energy-dependent transport or efflux pump todecrease intracellular accumulation of drug by extruding xenobioticsfrom the cell. This P-glycoprotein has been identified in normal tissuesof secretory endothelium, such as the biliary lining, brush border ofthe proximal tubule in the kidney and luminal surface of the intestine,and vascular endothelial cells lining the blood brain barrier, placentaand testis.

[0004] It is believed that the P-glycoprotein efflux pump preventscertain pharmaceutical compounds from transversing the mucosal cells ofthe small intestine and, therefore, from being absorbed into thesystemic circulation. A number of known non-cytotoxic pharmacologicalagents have been shown to inhibit P-glycoprotein, including cyclosporinA (also known as cyclosporine), verapamil, tamoxifen, quinidine andphenothiazines, among others. Many of these studies were aimed atachieving greater accumulation of cytotoxic drugs inside tumour cells.In fact, clinical trials have been conducted to study the effects ofcyclosporine on the pharmacokinetics and toxicities of paclitaxel(Fisher et al., Proc. Am. Soc. Clin, Oncol., 13: 143, 1994); doxorubicin(Bartlett et al., J. Clin, Onc-12:835-842, 1994); and etoposide (Lum etal., J. Clin, Onc, 10:163542, 1992), all of which are anti-cancer agentsknown to be subject to multidrug resistance (MDR). These trials showedthat patients receiving intravenous cyclosporine prior to or togetherwith the anti-cancer drugs had higher blood levels of those drugs,presumably through reduced body clearance, and exhibited the expectedtoxicity at substantially lower dosage levels. These findings tended toindicate that the concomitant administration of cyclosporine suppressedthe MDR action of P-glycoprotein, enabling larger intracellularaccumulations of the therapeutic agents. For a general discussion of thepharmacologic implications for the clinical use of P-glycoproteininhibitors, see Lum et al., Drug Resist, Clin, Onc, Hemat., 9: 319-336(1995); Schinkel et al., Eur, J. Cancer, 31A: 1295-1298 (1995).

[0005] In the aforedescribed studies relating to the use of cyclosporineto increase the blood levels of pharmaceutical agents subject toP-glycoprotein mediated resistance, the active agents and thecyclosporine were administered intravenously. No suggestion was made inthese publications that cyclosporine or other substances believed toinhibit the P-glycoprotein efflux pump could be orally administered tosubstantially increase the bioavailability of orally administeredanti-cancer drugs and other pharmaceutical agents which are themselvespoorly absorbed from the gut without producing highly toxic sideeffects. Indeed, in the 1995 review paper cited above, Lum et al. showedthat concomitant IV administration of MDR inhibitors andchemotherapeutic agents subject to MDR increased toxicity levels andexacerbated the patients' serious side effects. Schinkel et al. brieflyadverted to the fact that MDR 1 and P-glycoprotein are abundant in themucosal cells of the intestine, and that this may affect the oralbioavailability of P-glycoprotein substrate drugs, but did not suggestor imply that the oral administration of MDR suppressing agents couldimprove the bioavailability of the orally unavailable agents.Furthermore, like Lum et al., Schinkel et al. warned that P-glycoproteininhibitors can dramatically increase toxicity in chemotherapy patientsand should, therefore, be used cautiously.

[0006] In an earlier publication, Schinkel et al. showed that absorptionof orally ingested ivermectin was increased in mice homozygous for adisruption of the MDR1 a gene in comparison with normal mice,demonstrating that P-glycoprotein played a major role in reducing thebioavailability of this agent (Cell 77: 491-502, 1994). In addition,this study also showed that the penetration of vinblastine into varioustissues was enhanced in the mutant mice. A more recent publication bySparreboom et al. (Proc. Natl. Acad. Sci. USA 94: 2031- 2035, 1997)confirms these studies by showing that uptake of oral taxol is increasedin these mice.

[0007] None of the published studies provided any regimen forimplementing the effective oral administration of otherwise poorlybioavailable drugs, e.g., indicating the respective dosage ranges andtiming of administration for specific target drugs andbioavailability-enhancing agents (bioenhancers) or demonstrating whichMDR-inhibiting agents are best suited for promoting oral absorption ofeach target drug or class of drugs.

[0008] Methods disclosed in the art for increasing gut absorption ofdrugs that have until now only been administered parenterally generallyfocus on the use of permeation and solubility enhancers as promotingagents, or the co-administration by intraluminal perfusion in the smallintestine or by the intravenous route of P-glycoprotein inhibitors,e.g., Leu et al., Cancer Chemother, Pharmacol., 35: 432436, 1995(perfusion or IV infusion of quinidine suppresses efflux of etoposideinto the lumen of the G.I. tract from the blood). But these methodssuffer from numerous drawbacks. The solubility and permeabilityenhancing agents are often either impractical or ineffective for oraladministration in the doses required and may interfere with thepharmacological activity of the target drug and/or other drugs given incombination with the target drug. Parenteral administration ofP-glycoprotein inhibitors in therapeutic (or near-therapeutic) dosesinto humans can cause severe clinical consequences. In the case ofquinidine, for example, IV administration may cause arrhythmias,peripheral vasodilation, gastrointestinal upset and the like.

[0009] In published PCT application WO 95/20980 (published Aug. 10,1995) Benet et al disclose a purported method for increasing thebioavailability of orally administered hydrophobic pharmaceuticalcompounds. This method comprises orally administering such compounds tothe patient concurrently with a bioenhancer comprising an inhibitor of acytochrome P450 3A enzyme or an inhibitor of P-glycoprotein-mediatedmembrane transport. Benet et al., however, provide virtually no meansfor identifying which bioavailability enhancing agents will improve theavailability of specific “target” pharmaceutical compounds, nor do theyindicate specific dosage amounts, schedules or regimens foradministration of the enhancing or target agents. In fact, although theBenet application lists dozens of potential enhancers (P450 3Ainhibitors) and target drugs (P450 3A substrates), the only combinationof enhancer and target agent supported by any experimental evidence inthe application is ketoconazole as the enhancer and cyclosporin A as thetarget drug.

[0010] Thus, a need for a safe and effective method for increasing thesystemic availability upon oral administration of drugs that areadministered parenterally still exists. Current administration of suchdrugs is limited to the parenteral route because they are not absorbedsufficiently or consistently when administered by the oral route.

[0011] In published PCT application WO97/15269 (published May 1, 1997)Broder et al teach that the combination of paclitaxel with cyclosporineorally achieves comparable local tissue concentrations to paclitaxeladministered via the intravenous route. Moreover, WO 97/15269 teachesthat ketoconazole has significant oral bioavailability-enhancingactivity whilst other MDR inhibitors such as verapamil, dipyridamole andmegestrol have less enhancing activity and progesterone even has none.Broder et al thus teaches that only certain P-glycoprotein inhibitorsincrease oral bioavailability. Moreover, the two most successfulbioenhancers, cyclosporine and ketoconazole both interact with P450 3A.

[0012] It has now been discovered that, surprisingly,9,10-dihydro-5-methoxy-9-oxo-N-[4-[2-(1,2,3,4-tetrahydro-6,7-dimethoxy-2-isoquinolinyl)ethyl]phenyl]-4-acridinecarboxamideor a salt thereof, especially, its hydrochloride salt, can be used tosubstantially increase the oral bioavailability of the otherwise poorlyavailable paclitaxel as well as its analogs and derivatives, preferablyof compounds of formula I

[0013] wherein R₁ and R₂ is hydrogen or hydroxy, R₃ is phenyl (Ph) orOC(CH₃)₃ and R₄ is CH₃CO (acetyl (Ac)) or hydrogen. 9,10-dihydro-5-methoxy-9-oxo-N-[4-[2-(1,2,3,4-tetrahydro-6,7,-dimethoxy-2-isoquinolinyl)ethyl] pheny]-4-acridinecarboxamide is a P-glycoproteininhibitor but does not inhibit with the cytochrome P-450 system.

[0014] Accordingly, the present invention relates to the use of 9,10-dihydro-5-methoxy-9-oxo-N-[4-[2-(1,2,3,4-tetrahydro-6,7,- dimethoxy-2-isoquinolinyl)ethyl] pheny]-4-acridinecarboxamide or a salt thereoffor the manufacture of a medicament for use in increasing thebioavailability of paclitaxel or an analog or derivative thereof. Suchuse would be carried out by oral administration of paclitaxel or ananalog or derivative thereof (the active agent) together with saidbioenhancer (9,10-dihydro-5-methoxy-9-oxo-N-[4-[2-(1,2,3,4-tetrahydro-6,7,- dimethoxy-2-isoquinolinyl)ethyl] pheny]-4-acridinecarboxamide).

[0015] Taxanes with anti-cancer activity are also included as activeagents in accordance with the present invention.

[0016] The present invention relates in another aspect to a method ofincreasing the oral bioavailability of pharmaceutical agents that arepoorly absorbed or not absorbed at all from the gastrointestinal tractor gut by pre-administering and/or simultaneously administering to asubject by the oral route one or a combination of agents known to beeffective in inhibiting the P-glycoprotein drug transport pump. Ifpre-administration is used, the bioavailability enhancing agent oragents must be administered in sufficient quantities and within a shortenough time period before administration of the drug whosebioavailability is to be increased (the “target drug” or “target agent”)so that a sufficient level of the enhancing agent remains at the site ofabsorption at the time of administration of the target agent toeffectively inhibit the activity of the P-glycoprotein or othermulti-drug transporter substances. 9,10-dihydro-5-methoxy-9-oxo-N-[4-[2-(1,2,3,4-tetrahydro-6,7,- dimethoxy-2-isoquinolinyl)ethyl] pheny]-4- acridinecarboxamide itself has verypoor bioavailability across the gut making it a particularly goodbioenhancer as it remains at the site of absorption to effectivelyinhibit the activity of the P-glycoprotein.

[0017] In a further aspect, the invention pertains to compositions ordosage forms for oral administration of pharmaceutical agents that wereheretofore available for parenteral administration only. A fourth aspectof the invention relates to the administration of such oral dosage formsor a combination thereof to patients for treatment of diseasesresponsive to taxol and derivatives or analogs thereof which arecontained therein.

[0018] The invention also pertains to pharmaceutical kits comprising oneor more oral dosage forms containing as the target agent taxol andderivatives or analogs thereof and one or more oral dosage formscontaining as the enhancing agent, 9,10-dihydro-5-methoxy-9-oxo-N-[4-[2-(1,2,3,4-tetrahydro-6,7,-dimethoxy-2-isoquinolinyl)ethyl]pheny]-4-acridinecarboxamide

[0019] The present invention pertains generally to increasing the oralabsorption and bioavailability upon oral administration ofpharmacologically active agents, particularly agents that are poorlyabsorbed or not absorbed at all from the gastrointestinal tract or gut.The preferred embodiments of the invention pertain to (a) a method forincreasing the oral bioavailability of antitumour agents, in particularpaclitaxel (currently marketed as TAXOL® by Bristol-Myers SquibbOncology Division) and its derivatives; other taxanes which exhibitantitumour activity; the semi-synthetic paclitaxel analog docetaxel(N-debenzoyl-N-tert-butoxycarbonyl-10-deacetyl paclitaxel), producedunder the trademark TAXOTERE® by Rhone-Poulenc Rorer S.A; (b) dosageforms and kits for oral administration of antitumour agents and otherdrugs heretofore administered only parenterally; and (c) methods oftreatment of cancer patients with such oral dosage forms or combinationsthereof.

[0020] The phrases “oral bioavailability” and “bioavailability upon oraladministration” as used herein refer to the systemic availability (i.e.,blood/plasma levels) of a given amount of drug administered orally to apatient.

[0021] The term bioenhancer (or enhancing agent) as used herein refersto a compound which enhances and thus increases the oral bioavailabilityof a compound which normally has poor oral bioavailability. The compoundwhose oral bioavailability is to be enhanced is referred to as theactive (or target) agent/drug. The bioenhancer (enhancing agent) of thepresent invention is 9,10-dihydro-5-methoxy-9-oxo-N-[4-[2-(1,2,3,4-tetrahydro-6,7,-dimethoxy-2-isoquinolinyl)ethyl] pheny]-4-acridinecarboxamide whilst the activeagent (target agent/drug) of the present invention is paclitaxel and itsderivatives or analogs.

[0022] Paclitaxel [2aR-[2aα,4 β,4αβ,6β,9α(αR*, βS*),−11α,,12α,12aα,12bα]]-β-(Benzoylamino)α-hydroxybenzene-propanoic acid6,12b-bis(acetyloxy)-12-(benzoloxy)2a,3,4-4a,5,6,9,10,11,12,12a,12b-dodecahydro-4,11-dihydroxy-4a,8,-13,13-tetramethyl-5-oxo-7,11-methano-1H-cyclodeca[3,4]benz-[1,2-b]oxet-9-ylester; 5β,20-epoxy-1,2α,4,7β,10β,13α-hexa-hydroxytax-11-en-9-one4,10-diacetate 2-benzoate 13-ester with(2R,3S)N-benzoyl-3-phenylisoserine; is a natural diterpene productisolated from the Pacific yew tree Taxus brevifolia). It is a member ofthe taxane family of terpenes. It was first isolated in 1971 by Wani etal. J. Am. Chem, Soc., 93:2325. 1971), who characterized its structureby chemical and X-ray crystallographic methods. One mechanism for itsactivity relates to paclitaxel's capacity to bind tubulin, therebyinhibiting cancer cell growth. Schiff et al., Proc. Natl, Acad, Sci.USA, 77:1561-1565 (1980); Schiff et al., Nature, 277:665-667 (1979);Kumar, J. Biol, Chem, 256: 10435-10441 (1981). For a review of synthesisand anticancer activity of some paclitaxel derivatives see: D. G. I.Kingston et al., Studies in Organic Chemistry vol. 26, entitled “Newtrends in Natural Products Chemistry 1986”, Attaur-Rahman, P. W. LeQuesne, Eds. (Elsevier, Amsterdam, 1986) pp 219-235.

[0023] Paclitaxel has been approved for clinical use in the treatment ofrefractory ovarian cancer in the United States (Markman et al., YaleJournal of Biology and Medicine, 64:583, 1991; McGuire et al., Ann.Intem, Med., 111:273,1989). It is effective for chemotherapy for severaltypes of neoplasms including breast (Holmes et al., J. Nat, Cancer Inst,83:1797, 1991) and has been approved for treatment of breast cancer aswell. It is a potential candidate for treatment of neoplasms in the skin(Einzig et al., Proc. Am. Soc. Clin, Oncol., 20:46) and head and neckcarcinomas (Forastire et al. Sem, Oncol, 20:56, 1990). The compound alsoshows potential for the treatment of polycystic kidney disease (Woo etal., Nature, 368:750. 1994), lung cancer and malaria.

[0024] Paclitaxel is only slightly soluble in water and this has createdsignificant problems in developing suitable injectable and infusionformulations useful for anticancer chemotherapy. Some formulations ofpaclitaxel for IV infusion have been developed utilizing CREMOPHOR EL™(polyethoxylated castor oil) as the drug carrier because of paclitaxel'saqueous insolubility. For example, paclitaxel used in clinical testingunder the NCI has been formulated in 50% CREMOPHOR EL™ and 50%dehydrated alcohol. CREMOPHOR EL™ however, when administeredintravenously, is itself toxic and produces vasodilation, labouredbreathing, lethargy, hypotension and death in dogs. It is also believedto be responsible for the allergic-type reactions observed duringpaclitaxel administration.

[0025] In an attempt to increase paclitaxel's solubility and to developmore safe clinical formulations, studies have been directed tosynthesizing paclitaxel analogs where the 2′ and/or 7-position isderivatized with groups that would enhance water solubility. Theseefforts have yielded prodrug compounds that are more water soluble thanthe parent compound and that display the cytotoxic properties uponactivation. One important group of such prodrugs includes the 2′-oniumsalts of paclitaxel and docetaxel, particularly the 2′-methyipyridiniummesylate (2′-MPM) salts.

[0026] Paclitaxel is very poorly absorbed when administered orally (lessthan 1 %); see Eiseman et al., Second NCI Workshop on Taxol and Taxus(September 1992); Stuffness et al. in Taxol Science and Applications(CRC Press 1995). Eiseman et al. indicate that paclitaxel has abioavailability of 0% upon oral administration, and Stuffness et al.report that oral dosing with paclitaxel did not seem possible since noevidence of antitumour activity was found on oral administration up to160 mg/kg/day. Moreover, no effective method has been developed toenable the effective administration of oral paclitaxel (i.e., a methodof increasing the oral bioavailability of paclitaxel) or of other oraltaxanes or paclitaxel analogs such as docetaxel which exhibit antitumouractivity. For this reason, paclitaxel has not until now beenadministered orally to human patients, and certainly not in the courseof treating paclitaxel-responsive diseases.

[0027] Docetaxel 2αR-[2aα,4β,4αβ,6β,9α(αR*,βS*),−11α,12α,12aα12bα]]-β-[[(1,1-Dimethylethoxy)carbonyl]-amino]-α-hydroxybenzenepropanoicacid 12b-(acetyloxy)-12-(benzoloxy)-2a,3,4,-4a,5,6,9,10,11,12,12a,12b-dodecahydro-4,6,11trihydroxy-4a,8,-13,13-tetramethyl-5-oxo-7,11-methano-1H-cyclodeca[3,4]benz-[1,2-b]oxet-9-yl ester;N-debenzoyl-N-(tert-butoxycarbonyl-10-deacetyltaxol has becomecommercially available as TAXOTERE® in parenteral form for the treatmentof breast cancer. To date no reference has been made in the scientificliterature to oral absorption of docetaxel in animals or patients.Docetaxel is a semisynthetic derivative of paclitaxel q.v., preparedusing a natural precursor, 10-deacetyl-baccatin III, extracted from theneedle of the European Yew tree.

[0028]9,10-dihydro-5-methoxy-9-oxo-N-[4-[2-(1,2,3,4-tetrahydro-6,7-dimethoxy-2-isoquinolinyl)ethyl]phenyl]-4-acridinecarboxamideand its synthesis is disclosed in granted European Patent No.0569380-derived from PCT application WO92/12132.

[0029] It has now been discovered that paclitaxel and related taxaneswith poor oral absorption profiles can be effectively administeredorally with sufficient systemic absorption to exhibit therapeuticactivity levels when said agents are co-administered orally with, anoral dose of9,10-dihydro-5-methoxy-9-oxo-N-[4-[2-(1,2,3,4-tetrahydro-6,7-dimethoxy-2-isoquinolinyl)ethyl]phenyl]-4-acridinecarboxamideand it salts known to inhibit the multidrug resistance, drug transportactivity of the P-glycoprotein intracellular pump.

[0030] The method of the invention for increasing the oralbioavailability of a paclitaxel and related taxanes with poor oralbioavailability of less than 10% comprises the oral administration of anoral absorption or bioavailability enhancing agent to a mammalianpatient (human or animal) simultaneously with, or prior to, or bothsimultaneously with and prior to the oral administration to increase thequantity and duration of absorption of the intact target agent into thebloodstream.

[0031] The orally administered enhancing agents which may be used inaccordance with the invention is9,10-dihydro-5-methoxy-9-oxo-N-[4-[2-(1,2,3,4-tetrahydro-6,7-dimethoxy-2-isoquinolinyl)ethyl]phenyl]-4-acridinecarboxamideor a salt thereof. The most preferred salt is the hydrochloride salt.

[0032] The class of orally administered target therapeutic agents whoseoral absorption is increased by the enhancing agents includes, but isnot limited to, the following;

[0033] Paclitaxel, other taxanes, docetaxel and derivatives and prodrugsof all the foregoing, particularly their 2′-MPM salts and other2′-methylpyridinium salts.

[0034] The dosage range of the enhancing agent to be co-administeredwith the target agent in accordance with the invention is about 0. 1 toabout 150 mg/kg preferably, from 5 to 50 mg/kg of patient body weight.More preferably 10 to 30 mg/kg and most preferably about 20 to 30 mg/kg.“Co-administration” of the enhancing agent comprehends administrationsubstantially simultaneously with the target agent (either less than 1hour before, preferably less than 0.5 hr. before, less than 0.5 hr.after or together), from about 0.5 to about 24 hr. before theadministration of the target agent, or both, i.e., with one or moredoses of the same or different enhancing agents given at least 0.5 hr.before and one dose given substantially simultaneously with (eithertogether with or immediately before or after) the target agent.Additionally, “co-administration” comprehends administering more thanone dose of target agent within 24 hrs after a dose of enhancing agent,in other words, the enhancing agent(s) need not be administered againbefore or with every administration of target agent, but may beadministered intermittently during the course of treatment.

[0035] The dosage range of orally administered target agents will varyfrom drug to drug based on its therapeutic index, the requirements ofthe condition being treated, the status of the subject and so forth. Themethod of the invention makes it possible to administer paclitaxel andderivatives or analogs thereof orally ranging from about 20 mg/m² toabout 1000 mg/m² (based on patient body surface area) or about 0.5-30mg/kg (based on patient body weight) preferably 2 to 20 mg/kg and mostpreferably 5 to 10 mg/kg as single or divided (2-3) daily doses, andmaintain the plasma levels of paclitaxel in humans in the range of10-500 ng/ml preferably 20 to 500 ng/ml for extended periods of time(e.g., 8-12 hours) after each oral dose.

[0036] These levels are at least comparable to those achieved with 96hour IV infusion taxol therapy (which causes the patient greatinconvenience, discomfort, loss of time, infection potential, etc.).Moreover, such plasma levels of paclitaxel are more than sufficient toprovide the desired pharmacological activities of the target drug, e.g.,inhibition of tubulin disassembly (which occurs at levels of about 0.1μM, or about 85 ng/ml) and inhibition of protein isoprenylation (whichoccurs at levels of about 0.03 μM, or about 25 ng/ml) which are directlyrelated to its antitumour effects by inhibiting oncogene functions andother signal-transducing proteins that play a pivotal role in cellgrowth regulation.

[0037] It may be suitable in some instances to administer to the subjecta higher initial loading dose of the target agent to achieve peak bloodlevels, followed by lower maintenance doses.

[0038] Two or more different enhancing agents and/or two or moredifferent target agents may be administered together, alternately orintermittently in all of the various aspects of the method of theinvention.

[0039] The present invention also comprehends methods of treatingmammalian patients afflicted with cancers, tumours, Kaposi's sarcoma,malignancies, uncontrolled tissue or cellular proliferation secondary totissue injury, and any other disease conditions responsive topaclitaxel, taxanes, docetaxel, prodrugs and derivatives of all theforegoing, paclitaxel 2′-MPM, and docetaxel 2′-MPM with orallyadministered dosage forms comprising one or more of those agents. Amongthe types of carcinoma which may be treated particularly effectivelywith oral paclitaxel, docetaxel, other taxanes, and their prodrugs andderivatives, are hepatocellular carcinoma and liver metastases, andcancers of the gastrointestinal tract, pancreas and lung. Examples ofnon-cancerous disease conditions which may be effectively treated withthese active agents administered orally in accordance with the presentinvention are uncontrolled tissue or cellular proliferation secondary totissue injury, polycystic kidney disease and malaria, includingchloroquine- and pyrimethamine-resistant malaria parasites (Pouvelle etal., J. Clin, Invest., 44: 413417, 1994).

[0040] The antitumour agents which heretofore were administered onlyparenterally can now be administered in accordance with the invention bythe oral route with sufficient bioavailability to providepharmacologically active blood concentrations which will be particularlyeffective in the treatment of patients with primary tumours andmetastases. Steady state plasma levels of Paclitaxel may be achievedupon oral co-administration with the enhancing agent of the inventionwithin the first week of the regime, preferably within the first fivedays and most preferably within the first three days of the regimen. Thelevels of the target agent achieved at steady state are comparable tothose achieved in patients by a 96-hour IV infusion of paclitaxel.

[0041] Oral bioavailability of paclitaxel and its analogs/derivativesadministered with9,10-dihydro-5-methoxy-9-oxo-N[4-2-(1,2,3,4-tetrahydro-6.7-dimethoxy-2-isoquinolinyl)ethyl]phenyl]-4-acridinecarboxamideand/or its salts is more than 20%, preferably more than 25%, morepreferably more than 30% and most preferably more than 50%. A range of20 to 200% oral bioavailability is achieved, preferably between 30 to100% and most preferably between 40 to 75%.

[0042] Maximum plasma concentration achieved may be more than 5 foldhigher, preferably about 10 fold higher when paclitaxel and/or itsanalogs/derivatives are administered orally in combination with thebioenhancer of the present invention. A 27% response rate was found intaxane-failure patients with metastatic breast cancer treated with acontinuous 96-hour infusion every three weeks (Seidman et al., J. Clin,Oncol.,14:1877, 1996). It is believed that similar results can beachieved with the treatment methods of the present invention, withoutthe discomfort, inconvenience and risks of prolonged IV infusions.

[0043] Furthermore, and quite significantly, the elimination-phaseconcentration in the blood of paclitaxel when administered orally asprovided herein, is approximately equal to that achieved with IVadministration, and these high, therapeutically effective levels, can bemaintained for as long as 8-12 hours after each administration.

[0044] Oral dosage forms of the target agents whose bioavailability isincreased by the co-administration of the enhancing agents may be in theform of conventional tablets, capsules, caplets, gelcaps, pills, liquids(e.g., solutions, suspensions or elixirs), lozenges and any other oraldosage forms known in the pharmaceutical arts. The liquid preparationsmay include, for example, paclitaxel or other taxane in a vehiclecomprising CREMOPHOR EL or other polythoxylated castor oil, alcoholand/or a polythoxylated sorbitan mono-oleate (e.g., TWEEN® 80, ICIAmericas, Inc.). Each dosage form includes an effective amount of atarget agent (for example, effective antitumour or antineoplasticamounts of an antitumour or antineoplastic agent) and pharmaceuticallyinert ingredients, e.g., conventional excipients, vehicles, fillers,binders, disentegrants, solvents, solubilizing agents, sweeteners,coloring agents and any other inactive ingredients which are regularlyincluded in pharmaceutical dosage forms for oral administration. Manysuch dosage forms and oral vehicles immediately after listings ofinactive ingredients therefor are set forth in Remington'sPharmaceutical Sciences, 17th edition (1985). Each dosage form alsocontains a pharmacologically effective amount. for example, an effectiveantineoplastic or tumour-reducing amount, of one of the target drugs.

[0045] Precise amounts of each of the target drugs in the oral dosageforms will vary depending on the age, weight, disease and condition ofthe patient. For example, paclitaxel dosage forms may contain sufficientquantities of paclitaxel to provide a daily dosage of about 20-1000mg/m² (based on patient body surface area) or about 2-30 mg/kg (based onpatient body weight) as single or divided (2-3) daily doses.

[0046] In establishing a treatment regimen for a particular patienttreated with the oral, target drug-containing dosage forms of theinvention, it is necessary to take into account the increasedbioavailability provided by the concomitant/or prior oral administrationof the enhancing agents.

[0047] Dosing schedules for the treatment method of the presentinvention, for example, the treatment of paclitaxel-responsive diseaseswith oral paclitaxel dosage forms co-administered with enhancing agents,can likewise be adjusted to account for the patient's characteristicsand disease status. Preferred dosing schedules for administration oforal paclitaxel are (a) the daily administration to a patient in needthereof of 1-3 equally divided doses providing about 20-1000 mg/m²(based on body surface area), with said daily administration beingcontinued for 1-4 consecutive days each 2-3 weeks, or (b) administrationfor about one day each week. The former schedule is comparable to use ofa 96- hour paclitaxel infusion every 2-3 weeks, which is considered bysome a preferred IV treatment regimen.

[0048] Oral administration of powerful chemotherapeutic agents inaccordance with the invention may actually decrease toxic side effectsin many cases as compared with currently utilized IV therapy. Ratherthan producing a sudden and rapid high concentration in blood levels asis usually the case with an IV infusion, absorption of the active agentthrough the gut wall (promoted by the enhancing agents), provides a moregradual appearance in the blood levels and a stable, steady-statemaintenance of those levels at or close to the ideal range for a longperiod of time.

[0049] Pursuant to another aspect of the invention, combination oraldosage forms are provided which contain fixed quantities of at least oneenhancing agent and at least one target agent. For example, such dosageforms can consist of tablets, capsules, caplets, gelcaps, pills,liquids, lozenges and any other conventional oral dosage formscontaining as active ingredients an effective oral bioavailabilityenhancing amount of an antitumour or anti-neoplastic agent, as well assuitable inactive ingredients. One such combination product includesfrom about 0.5 to about 15 mg/kg of the active bioenhancer of thepresent invention together with about 20 to about 1000 mg/m² (based onaverage patient body surface area) of paclitaxel, docetaxel, othertaxanes or paclitaxel or docetaxel derivatives such as paclitaxel 2-MPMor docetaxel 2′-MPM.

[0050] The co-administration of enhancing agents with the target drugspromotes not only the oral bioavailability of those agents but alsoenables their use in the treatment of tumours at sites highly protectedby MDR, e.g., the testes and the brain. Another aspect of the presentinvention is, thus, a method of delivering antitumour drugs to tumoursites protected by MDR through the oral co-administration of enhancingagents and the antitumour agents, making it possible to treat braintumours such as glioblastoma multiforme.

[0051] Yet another aspect of the present invention is a method ofdelivering an active paclitaxel metabolite to a disease site attherapeutic levels to treat paclitaxel responsive diseases. The major invivo metabolites of paclitaxel have been identified, particularly thefollowing hydroxylated paclitaxel metabolises A, B and C:

[0052] A: R₁—H₁R₂═OH; B: R₁═OH, R₂═H; C: R₁═OH, R₂═OH (Paclitaxel: R₁═H,R₂═H)

[0053] In certain in vitro tests metabolite B shown above (also referredto in the literature as metabolise M4) has been found to have a highertherapeutic index (ratio of toxic concentration level to effectiveconcentration level) than paclitaxel in some human tumour cell lines.The invention possibly enables delivery of enhanced amounts ofmetabolite B and other active metabolites of paclitaxel to tumour sitesbecause upon oral administration all of the administered paclitaxel willpass through the liver and undergo metabolism by liver microsomes,yielding more of each metabolite in the systemic circulation than isachieved with IV administration.

[0054] An additional aspect of the invention relates to kits to be usedin the treatment of mammalian patients suffering from conditionsresponsive to any pharmacologically active target agents whose oralabsorption and bioavailability is increased by an enhancing agent. Thesekits include one or more oral dosage forms of at least one enhancingagent and one or more oral dosage forms of at least one target agent, orone or more dosage forms which comprise both.

[0055] By way of illustration, a kit of the invention may include one ormore tablets, capsules, caplets, gelcaps or liquid formulationscontaining the bioenhancer of the present invention, and one or moretablets, capsules, caplets, gelcaps or liquid formulations containingpaclitaxel in dosage amounts within the ranges described above. Suchkits may be used in hospitals, clinics, physician's offices or inpatients' homes to facilitate the co-administration of the enhancing andtarget agents. The kits should also include as an insert printed dosinginformation for the co-administration of the enhancing and targetagents.

[0056] The subject kits may also include combinations of differentenhancing agents and/or combinations of target agents. For example, akit may include oral dosage forms9,10-dihydro-5-methoxy-9-oxo-N-[4-[2-(1,2,3,4-tetrahydro-6,7-dimethoxy-2-isoquinolinyl)ethyl]phenyl]-4-acridinecarboxamideas enhancing agent, with paclitaxel alone as the target agent or with acombination of paclitaxel and another antitumour drug. The second targetagent should be (like paclitaxel) a drug that exhibits poor oralbioavailability but with co-administration of enhancing agents canachieve therapeutically effective blood levels upon oral administration.The target agent may co-exist with the enhancing agent in the samedosage form or may be in a separate dosage form.

[0057]FIG. 1.

[0058] Comparison of paclitaxel concentration with time after oraladministration of paclitaxel in combination with GF120918 compared tooral administration of paclitaxel on its own.

EXAMPLE 1 Materials and Methods for Animal Studies

[0059] Female FVB Wild-type mice, aged between 10 to 14 weeks andweighing between 20 to 30 g were used.

Drugs and Administration Route

[0060] Paclitaxel (Taxol™) from, Bristol Myers Squibb was dissolved invehicle consisting of Cremophor EL:Ethanol (1:1).(v/v) at aconcentration of 6 mg/ML. Paclitaxel was given orally at a dose of 10mg/kg. Oral drug administration was done by injection with a bluntneedle via the oesophagus into the stomach.

[0061] 9, 10-dihydro-5-methoxy-9oxo-N-[4-[2-(1,2,3,4-tetrahydro-6,7,-dimethoxy-2-isoquinolinyl)ethyl]phenyl]-4-acridinecarboxamide(GF120918) (hydrochloride salt) from GlaxoWellcome was dissolved invehicle consisting of 0.5%(w/v) hydroxypropylmethylcellulose (K15MPremium) with 1% (w/v) Tween 80 in Water for Irrigation giving a finalconcentration of 2.5 mg/mL. GF120918 was administered orally at a doseof 25 mg/kg. Oral administration was done by injection with a bluntneedle via the oesophagus into the stomach.

Preparation of StockVehicle and GF120918 Suspension

[0062] Concentrated stock vehicle preparation for GF120918 (1L): weigh10 g of hydroxypropylmethylcellulose into a suitable container. On a hotplate, heat approximately 500 g of water for irrigation to no less than80° C. Stop heating the mixture and commence stirring with a magneticstir bar and stir plate. Continue mixing and gradually add thehydroxypropylmethylcellulose Leave stirring for at least 15 minutes toensure dispersion. Continue stirring until the solution has cooled toapproximately 30° C., then add 20 g of Tween 80 and mix thoroughly forapproximately 5 to 10 minutes. Add sufficient water for irrigation toachieve a final weight of 1,000 g and mix. Dispense the HPMC solutioninto a suitable container and store at 2 to 8° C., protected from light.

[0063] 2.2 mg GF120918X/ml Suspension : Weigh 0.206 g of GF120918 into asuitable container and mix with sufficient water for irrigation to makea slurry. Transfer 37.5 mL of the measured concentrated stock vehicle toa graduated cylinder and add the GF120918 slurry on top of thisconcentrated stock vehicle. Rinse all the transfer vessels with waterfor irrigation and transfer to the graduated cylinder until a finalvolume of 75 mL is obtained. Mix by inversion for approximately 10minutes to ensure that the test article is dispersed evenly throughoutthe suspension. Add additional water for irrigation if the meniscus ofthe preparation has fallen below 75 mL after mixing. Dispense the 75 mLof suspension into a labelled container and mix the suspension with aPolytron homogeniser for up to one minute. After mixing with thePolytron homogeniser, continue to mix the suspension with a magneticstir bar and stir plate. Dispense the dose preparation into labelledamber containers. Store the dose preparation between 18 and 25° C.,protected from light. The material should be mixed with a magnetic stirbar and stir plate at least 30 minutes before and during dosing theanimals.

Test Groups

[0064] The animals were divided into two test groups A and B.

[0065] Group A (control): consisted of a total of 42 animals. Paclitaxelwas administered to the mice orally as described above. This group didnot receive any GF120918, only vehicle. Blood samples were collectedafter 0.5, 1, 2, 3, 4, 6, and 8 hours by anaesthetising the animalsusing diethyl ether, fixation on their back, with their chest in anupright position, so that blood could be collected by heart punctionusing a 1 mL syringe filled with 10 μL of heparin solution asanticoagulant. The number of animals per sampling time point was 6. Theblood samples were centrifuged in a Eppendorf microvial for 5 min at1500 g. The supernatant plasma fraction was transferred to a clean vialand stored at −20° C. until analysis.

[0066] GroupB (test) : consisted of 60 animals. Both Paclitaxel andGF120918 were administered to the mice orally as described above Bloodsamples were collected as described for Group A after 0.5, 1, 2, 3, 4,6, 8, 12, 16 and 24 hours with 6 animals per sampling time point.

Analytical Methods

[0067] Analysis of paclitaxel levels in the plasma samples was performedusing a validated HPLC methodology ((Bioanalytical report “Analysis ofpaclitaxel in human plasma by high performance liquid chromatography(HPLC) with UV detection” version 2.0, Approval dated: 1st April 1996).

Results

[0068]FIG. 1 clearly shows that compared to oral paclitaxel withoutGG120918 (control) the combination of paclitaxel with GF120918 (test)significantly increases the systemic exposure of wild mice topaclitaxel. More specifically in FIG. 1, GF120918 increases the AUCvalue 5 fold, and the plasma concentration of paclitaxel is increased 7fold.

[0069] Previous experiments gave an AUC value of 710±100 forintravenously administered tpaclitaxel (without GF120918) giving anapproximate increase of 60% bioavailability with oral paclitaxel incombination with GF120918.

1. A combination of 9,10-dihydro-5-methoxy-9-oxo-N-[4-[2-(1,2,3,4-tetrahydro-6,7,-dimethoxy-2-isoquinolinyl)ethyl]pheny]-4-acridinecarboxamide or a saltthereof and paclitaxel and; its analogs or derivatives.
 2. A combinationaccording to claim 1, wherein paclitaxel and its analogs or derivativesare compounds of formula (I)

wherein R₁ and R₂ is hydrogen or hydroxy, R₃ is phenyl (Ph) or OC(CH₃)₃and R₄ is CH₃CO (acetyl (Ac)) or hydrogen.
 3. A combination according toclaim 2, wherein the compounds of formula (I) are paclitaxel ordocetaxel.
 4. Use of a 9,10-dihydro-5-methoxy-9-oxo-N-[4-[2-(1,2,3,4-tetrahydro-6,7,-dimethoxy-2-isoquinolinyl)ethyl]pheny]-4-acridinecarboxamide or a saltthereof for the manufacture of a medicament for use as a bioenhancertogether with paclitaxel and its analogs or derivatives as the activeagent in the treatment of a patient by oral administration.
 5. Useaccording to claim 4, wherein paclitaxel and its analogs or derivativesare compounds of formula I

wherein R₁ and R₂ is hydrogen or hydroxy, R₃ is phenyl (Ph) or OC(CH₃)₃and R₄ is CH₃CO (acetyl (Ac)) or hydrogen.
 6. Use according to claim 5,wherein compounds of formula I are paclitaxel or docetaxel.
 7. Useaccording to claims 4 to 6, wherein the bioenhancer is administeredbefore the administration of the active agent.
 8. Use according to anyof claims 4 to 7, wherein the bioenhancer and the active agent are eachadministered in separate oral dosage forms.
 9. Use according to any ofclaims 4 to 8, wherein the bioenhancer and the active agent areadministered together in a combination oral dosage form.
 10. Useaccording to any of claims 4 to 9, wherein the patient is a humanpatient.
 11. Use according to any of claims 4 to 10, wherein two or moredoses of the active agent are administered after a single dose of thebioenhancer.
 12. Use according to any of claims 4 to 11, wherein theactive agent comprises about 0.5 to 30 mg/kg paclitaxel based on thepatient's weight.
 13. Use according to any of claims 5 to 12, whereinthe bioenhancer comprises about 10 to 30 mg/kg of 9,10-dihydro-5-methoxy-9-oxo-N-[4-[2-(1,2,3,4-tetrahydro-6,7,-dimethoxy-2-isoquinolinyl)ethyl]pheny]-4-acridinecarboxamide.
 14. Amethod of increasing bioavailability upon oral administration tomammalian patient of a pharmacologically active agent comprisingco-administration to the patient of the active agent and an oralbioenhancer which is 9,10dihydro-5-methoxy-9-oxo-N-[4-[2-(1,2,3,4-tetrahydro-6,7,-dimethoxy-2-isoquinolinyl)ethyl]pheny]-4-acridinecarboxamide.